<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div class="list" style="display:flex ; text-align: center;">

    </div>
    <button class="prev">上一页</button>
    <button class="next">下一页</button>
</body>

</html>
<script>

    var page = 1;//保存当前页面
    function objToSearchString(obj) {
        var str = '';
        //遍历对象, 将对象obj的每个属性名和属性值拼接为 key=value& 的格式
        for (var key in obj) {
            str += `${key}=${obj[key]}&`
        }
        //返回拼接好的字符串  key=value&key=value&key=value&key=value
        return str.slice(0, str.length - 1);
    }
    function ajax(method, url, params, cb) {
        var xhr = new XMLHttpRequest();//1.创建请求对象
        xhr.open(method, url + "?" + objToSearchString(params));//2.配置请求对象
        xhr.onreadystatechange = function () {//3.设置回调函数
            if (xhr.readyState == 4) {
                cb(JSON.parse(xhr.responseText));
            }
        }
        xhr.send();//4.发送请求
    }
    document.querySelector('.prev').onclick = function () {
        if (page == 1) {
            document.querySelector('.prev').disabled = true;
        } else if(page > 1){
            document.querySelector('.next').disabled = false;
            ajax('get', `https://yantianfeng.com/api/emotion`, { page: --page, count: 10 }, function (data) {
                var str = data.emotions.map((item, index) => {
                    return `<div> <img src="${item.url}" /> <div> ${item.title} </div> </div>`
                }).join('')
                //渲染表情
                document.querySelector('.list').innerHTML = str;
            });
        }
    }

    document.querySelector('.next').onclick = function () {
        if (page == 4) {
            document.querySelector('.next').disabled = true ;
        }else if (page<4){
            document.querySelector('.prev').disabled = false;
            ajax('get', `https://yantianfeng.com/api/emotion`, { page: ++page, count: 10 }, function (data) {
                // console.log(data);
                var str = data.emotions.map((item, index) => {
                    return `<div> <img src="${item.url}" /> <div> ${item.title} </div> </div>`
                }).join('')
                //渲染表情
                document.querySelector('.list').innerHTML = str;
            });
        }
    }
</script>